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From: Eric Biggers <ebiggers@kernel.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>,
	Satya Tangirala <satyat@google.com>,
	linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-f2fs-devel@lists.sourceforge.net,
	linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org
Subject: Re: [PATCH v4 3/7] iomap: support direct I/O with fscrypt using blk-crypto
Date: Wed, 22 Jul 2020 16:12:58 -0700
Message-ID: <20200722231258.GA83434@sol.localdomain> (raw)
In-Reply-To: <20200722224407.GR15516@casper.infradead.org>

On Wed, Jul 22, 2020 at 11:44:07PM +0100, Matthew Wilcox wrote:
> On Wed, Jul 22, 2020 at 03:34:04PM -0700, Eric Biggers wrote:
> > > Which means you are now placing a new constraint on this code in
> > > that we cannot ever, in future, zero entire blocks here.
> > > 
> > > This code can issue arbitrary sized zeroing bios - multiple entire fs blocks
> > > blocks if necessary - so I think constraining it to only support
> > > partial block zeroing by adding a warning like this is no correct.
> > 
> > In v3 and earlier this instead had the code to set an encryption context:
> > 
> > 	fscrypt_set_bio_crypt_ctx(bio, inode, pos >> inode->i_blkbits,
> > 				  GFP_KERNEL);
> > 
> > Would you prefer that, even though the call to fscrypt_set_bio_crypt_ctx() would
> > always be a no-op currently (since for now, iomap_dio_zero() will never be
> > called with an encrypted file) and thus wouldn't be properly tested?
> > 
> > BTW, iomap_dio_zero() is actually limited to one page, so it's not quite
> > "arbitrary sizes".
> 
> I have a patch for that
> 
> http://git.infradead.org/users/willy/pagecache.git/commitdiff/1a4d72a890ca9c2ea3d244a6153511ae674ce1d8

No you don't :-)  Your patch is for iomap_zero_range() in
fs/iomap/buffered-io.c.  It doesn't touch fs/iomap/direct-io.c which is what
we're talking about here.

> It's not going to cause a problem for crossing a 2^32 boundary because
> pages are naturally aligned and don't get that big.

Well, the boundary can actually occur at any block.  But it's not relevant here
because (a) fs/iomap/buffered-io.c doesn't yet support encryption anyway, since
neither ext4 nor f2fs use it; and (b) iomap_zero_range() just writes to the
pagecache, and the bios aren't actually issued until ->writepages().

- Eric

  reply index

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-20 23:37 [PATCH v4 0/7] add support for " Satya Tangirala
2020-07-20 23:37 ` [PATCH v4 1/7] fscrypt: Add functions for direct I/O support Satya Tangirala
2020-07-22 17:04   ` Jaegeuk Kim
2020-07-20 23:37 ` [PATCH v4 2/7] direct-io: add support for fscrypt using blk-crypto Satya Tangirala
2020-07-22 17:05   ` Jaegeuk Kim
2020-07-20 23:37 ` [PATCH v4 3/7] iomap: support direct I/O with " Satya Tangirala
2020-07-22 17:06   ` Jaegeuk Kim
2020-07-22 21:16   ` Dave Chinner
2020-07-22 22:34     ` Eric Biggers
2020-07-22 22:44       ` Matthew Wilcox
2020-07-22 23:12         ` Eric Biggers [this message]
2020-07-22 23:26       ` Eric Biggers
2020-07-22 23:32         ` Darrick J. Wong
2020-07-22 23:43           ` Eric Biggers
2020-07-23 22:07       ` Dave Chinner
2020-07-23 23:03         ` Eric Biggers
2020-07-24  1:39           ` Dave Chinner
2020-07-24  3:46             ` Eric Biggers
2020-07-24  5:31               ` Dave Chinner
2020-07-24 17:41                 ` Eric Biggers
2020-07-25 23:47                   ` Dave Chinner
2020-07-25 23:59                     ` Dave Chinner
2020-07-26  2:42                     ` Eric Biggers
2020-07-27 17:16                       ` Eric Biggers
2020-07-20 23:37 ` [PATCH v4 4/7] ext4: " Satya Tangirala
2020-07-22 17:07   ` Jaegeuk Kim
2020-07-20 23:37 ` [PATCH v4 5/7] f2fs: " Satya Tangirala
2020-07-21 20:11   ` Jaegeuk Kim
2020-07-20 23:37 ` [PATCH v4 6/7] fscrypt: document inline encryption support Satya Tangirala
2020-07-22 17:01   ` Jaegeuk Kim
2020-07-20 23:37 ` [PATCH v4 7/7] fscrypt: update documentation for direct I/O support Satya Tangirala
2020-07-21  0:47   ` Eric Biggers
2020-07-22 16:57     ` Jaegeuk Kim
2020-07-21  0:56 ` [PATCH v4 0/7] add support for direct I/O with fscrypt using blk-crypto Eric Biggers

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